Downhole pumps are used to pump fluid from a formation by moving a piston relative to a bore. Clearance is provided between the piston and the bore to ensure that downhole debris does not negatively affect the performance of the downhole pump. However, this clearance allows for leakage between the piston and the bore. Further, in some instances the pump may not be completely full when pumping. As a result, pump fillage affects the amount of fluid produced by a pump.
Certain examples are shown in the above-identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify the same or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness. Additionally, several examples have been described throughout this specification. Any features from any example may be included with, a replacement for, or otherwise combined with other features from other examples.